1. Field of the Invention
The present invention relates generally to a cellular phone subsidy lock, and more particularly pertains to a cellular phone subsidy lock which ensures that a cellular phone, sold to an end-user at a price subsidized by a cellular carrier, is activated only on the subsidizing carrier's network, and not on a competitor's network, particularly where the competitor's network likewise implements a different subsidy lock methodology.
2. Discussion of the Prior Art
The following acronyms and definitions are used throughout this patent application:
Carrier Code--code specific to one carrier; PA1 CKSUM--Checksum for error checking; PA1 GIM--Group Identification Mark; PA1 ESN--Electronic Serial Number; PA1 MIN--Mobile Identification Number (cellular phone number); PA1 NAM--Number Assignment Module (programmed with many parameters required to operate a cellular phone such as ESN, GIM, MIN, SID, SOC); PA1 SID--System Identification Number (carrier identifier); PA1 SOC--System Operator Code, PA1 a front-end requirement ensures that the initial activation (NAM programming) is performed only on one of the purchasing carrier's systems; PA1 a back-end requirement ensures that once the initial activation programming is successfully completed with the unlock code, and the subsidy lock has not been removed or disabled, subsequent activations may be performed only by a repetition of the same steps; PA1 the process is secure against another carrier attempting to reprogram the subsidized phone; PA1 a carrier is able to disable the subsidy lock to allow subsequent activations without entry of a code; PA1 a phone is still allowed to roam; PA1 the subsidy lock is easy for carriers to implement for all phones from one manufacturer; PA1 the subsidy lock feature provides two choices to optionally implement during manufacture, (1) implement no subsidy lock restriction on activation, or (2) implement a subsidy lock restriction for all activations, until disabled or removed.
In known cellular communication systems, a subscriber or user typically purchases a mobile communication phone or hand held phone or cellular phone which provides the user with access to the cellular communication system. When the user purchases the cellular phone, the phone is assigned a mobile identification number (MIN). When operating, the phone uses its previously programmed electronic serial number (ESN) and its MIN to identify itself to the cellular communication system or network (e.g. Cellular One, Bell Atlantic, etc.), and therefore, such numbers identify the user for billing and other purposes.
The Number Assignment Module (NAM) of a cellular phone stores information regarding the cellular phone, such as the MIN, the ESN, a country code, at least one SID, an optional password, and the like. Much of the information stored within the NAM is required for the cellular phone to access the carrier's system or network.
Cellular phone carriers frequently provide subsidized cellular phones to customers. As an example, a subscriber customer or end user would obtain a subsidized phone in return for a promise of continued usage of a phone system's service for a predetermined duration of time or subsidy period.
Various vendors have implemented specific methodologies regarding what procedures to implement in regards to maintaining the subsidized phone for the predetermined duration or the subsidy period.
For instance, in U.S. Pat. No. 5,864,757, issued to John P. Parker on Jan. 26, 1999, and assigned to BellSouth Corporation, there is disclosed an apparatus and method for locking and unlocking mobile telecommunication handsets or other devices.
Another such system is disclosed and described in U.S. Pat. No. 5,444,764, issued to Dawn M. Galecki on Aug. 22, 1995, and assigned to Motorola, wherein a SIM card is inserted into a radiophone for providing subscriber identification data.
For a manufacturer of a cellular phone, however, their phones may be sold to various service providers or carriers. Consequently, it would be advantageous to provide a single subsidy lock system which could be capable of implementing various phone carriers subsidy lock algorithms or methodologies or implement a subsidy lock disable or remove feature for those carriers that do not have or do not choose to use a subsidy lock algorithm or methodology.
In the carrier systems which implement a subsidy lock algorithm or methodology, it is also advantageous to enable the cellular phone for an unspecified time but terminable at a future time when used on the subsidized cellular carrier's system to thereby ensure that the subsidizing carrier receives compensation for the user's purchase of a cellular phone. Therefore, at the option of the subsidizing carrier, the subsidy lock can either be entirely disabled or only accessed so that an activation of the phone can occur.